Transmission buzz

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4,021
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New England
My 1993 Chevy C1500 with 4L60E has had a somewhat annoying buzz for a while now. It only occurs when in a drive gear (not park or neutral) and only when under no/light throttle. This is a fairly common issue as I've heard it on other trucks but that doesn't help me figure out what's going on. I can only describe it as a loud buzzing (heard from inside the cab with the windows down) coming from the transmission. It doesn't vary with speed but as soon as you go beyond extremely light throttle will instantly disappear. Any ideas? The transmission currently has about 25,000 miles on it and operates properly.
 

cchase

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4,021
Location
New England
Originally Posted By: simple_gifts
Are you sure it is not a sympathetic vibration?
This is a fairly audible buzzing noise, like you would imagine a pump motor to make (not suggesting this is the cause, just a similar noise) coming from the transmission.
 
Messages
26,152
Location
MA, Mittelfranken.de
I found this some time ago and copied it, i dont remember where so i can credit them but its good info. Number 36 sound like your problem. Common failures on 4L60E, symptom -> cause -> any possible repair: 1. Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell. It is possible to remedy a fluid problem by removing the checkball from its cage in the case in the rear of the trans may help (must remove valvebody), or adding a high-viscosity additive such as Lucas Transmission additive or other seal restorer product. May also have worn boost valve (can replace in the pan). 2. 1-2 shift does not happen at WOT until you let off the gas: Best case: try replacing the TPS. Middle case: leak in the 2nd gear apply circuit (servo assembly or 1-2 accumulator). Doublecheck by using the pressure gauge and watch for a big drop when the PCM commands 2nd gear. Worst case: poor line pressure rise (see below). 3. 1-2 Shift shudder at WOT; delayed or abnormal 1-2 shift; There's a problem ONLY on the 1-2 shift: 1-2 accumulator piston cracked or stuck cocked in the bore. Check the yellow spring inside the accum housing for breakage. Also, if the accumulator housing walls are scored, the housing must be replaced. Easy fix in the pan. 4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace. 5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must come out to access VSS. 6. No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive (in 2) until you can get it fixed. 7. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal; sunshell is fractured. R&R. Try not to run or drive the car or further damage could result. 8. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to run or drive the car or further damage could result. 9. No 2nd or 4th gear: 2-4 band is slipping. Servo seals may be damaged (can be fixed without removing trans. Otherwise, 2-4 band is worn out. R&R. 10. Trans shifts into gear harshly, 3rd gear starts, manual 2nd available but no 1st, no 4th, and no TCC lockup: No power to transmission, or trans is in limp-home mode. Check trans fuse underhood, and make sure transmission electrical connector is plugged in. Easy fix. 11. No 1st or 4th available: trans shifts 2nd to 3rd by itself in D or OD : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM. 12. No 2nd or 3rd available: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM. 13. No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace TC). 14. TCC always locked: TCC apply solenoid circuit shorted to ground, TCC solenoid blockage (easy fix in pan), or TC broken (must remove trans and replace TC). 15. Horrible noise in 4th and feels like the brakes are on: overrun clutches are applying due to a cracked or leaking forward piston. Overrun clutches will be worn out after 30 seconds of this behavior. Car can be safely driven in D. R&R. 16. Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R. Also try a transmission flush with BG brand products (Firestone stocks it). 17. No forward movement in OD or D, but L2, L1 and R work: Forward sprag is broken. R&R. Try not to run or drive the car or further damage could result. 18. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break. 19. Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign. R&R. 20. Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R sooner rather than later. 21. No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan and find the leak. If out of fluid, avoid running the engine until the trans is refilled to avoid pump damage. To check for pump failure, check fluid level with the engine off, then start the engine and recheck fluid level. If level does not go down when engine is running, the pump is broken. 22. Transmission does not shift automatically, only manually: Swap in a known-good PCM, check wiring, check other sensors such as VSS and TPS. 23. 3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it. 24. Car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmision is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the underhood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode. 25. Fluid leak out of the front of trans where the converter connects; partial or full loss of movement: Front pump bushing walked out. R&R. May have to replace converter also if hub is scored. Note that a leaking front seal usually means the bushing is walking out (i.e. call your local trans shop and schedule an appt.). 26. Torque converter shudder in 4th while lockup is engaged, problem goes away when the brake pedal is pressed slightly to unlock converter: Have a shop verify line pressure, and provided no valves in the TCC hydraulic circuit are worn, replace the torque converter. Also, Lubegard Shudder Fix will at least fix this for awhile. Or try a transmission flush by a shop that uses BG brand products. 27. Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS. 28. All fluid pumped out through the vent tube: Plugged cooler line. Flush the transmission cooler and cooler lines. Also could be overfiled transmission. 29. Car acts like it's in OD in neutral, car is locked stationary in R, engine feels loaded in P, all four forward positions work fine:Internal crossleak feeding the forward clutches all the time. Most likely a cracked input housing. R&R required. Car can safely be driven gently in forward gears until the repair. 30. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a torrington bearing or a planetary bearing is on its way out. Trans will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts), but requires R&R. It is drivable until it breaks. 31. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R. 32. 2-3 clunk/ bang under light load, but other gears shift fine: Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift. During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case. This is a normal condition. No repairs should be attempted. This is a bulletin from GM that i found. it is considered a normal condition. i'd still do the preliminary checks to make sure all driveline components are in good condition. 33. Gets stuck in third gear but able to be manually shifted through the gears. (No OD). Replacing the 3/2 downshift solenoid in the tranny pan fixed the problem. 34. When placed in drive, won't start in 1st but then sometimes it will then second and third shakes and then clears up: Sprag clutch flipped and broke the cage, but sometimes you can make it flip back over, that's why the death rattle in 2nd and 3rd. 35. No 2nd and 4th? but has reverse: The 2/4 band is broken, not applying, or burnt to a crisp. 36. Whistling noise from transmission: Teflon wore off your pump bushing. they wear off, and make a funny little buzzing sound, then when you put it in gear, the pressure goes up, and the torque converter is pushed forward slightly, and then no noise. The sound is temperature temperamental too.
 

cchase

Thread starter
Messages
4,021
Location
New England
Trav, Interestingly I found a list very similar to that somewhere else but didn't see #36. My issue/questions are: - I wouldn't call it a "whistling" sound, it's very definitely a buzz, almost like a door buzzer on an older car/truck might sound only not as aggressive. - Would a problem such as #36 even exist on a transmission with under 30,000 miles of light use? The truck doesn't even get driven from about December through April. - So far I haven't noticed any ambient or transmission temperature correlation to this noise.
 
Messages
26,152
Location
MA, Mittelfranken.de
Hard to say but sometimes even young units have issues. Teflon wear on the bushing is not a critical event just an annoyance if that was the case. A slightly clogged filter can cause the noise you describe by increasing the pressure. Higher than normal pressure can cause a buzzing noise. Try the cheap way first, do a fluid and filter change first, put a bottle of lubeguard red in it for good measure.
 

cchase

Thread starter
Messages
4,021
Location
New England
Originally Posted By: Trav
Try the cheap way first, do a fluid and filter change first, put a bottle of lubeguard red in it for good measure.
Good advice. This is what I am considering doing anyway since it's coming up on 30,000 miles and the fluid likely has a lot of contaminants at this point. Not looking forward to dropping the pan, however.
 
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1,715
Location
VA
I had an '87 Caprice with the 700R4 that made a noise like you describe. I bought the car at 150,000 and immediately put in a shift kit, drain plug, and external cooler. I can't remember whether the noise was there before that, but the trans never had any problems through 205,000 miles when I sold the car. That noise was unique enough that I still notice it occasionally in parking lots.
 
Messages
717
Location
MKE
Hello Trav, We have a 2003 Toyota Sienna, especially recently when it is cold early in the morning (4-5 AM) I hear an increasing RPM-like sound at 30-35 mph. When it finally shifts the sound is not there anymore.It sounds like engine, increases with pressing the accelerator, goes away if I let my foot off gas even without shifting. What can it be?
Originally Posted By: Trav
Hard to say but sometimes even young units have issues. Teflon wear on the bushing is not a critical event just an annoyance if that was the case. A slightly clogged filter can cause the noise you describe by increasing the pressure. Higher than normal pressure can cause a buzzing noise. Try the cheap way first, do a fluid and filter change first, put a bottle of lubeguard red in it for good measure.
 
Messages
26,152
Location
MA, Mittelfranken.de
How long have you had this van? The reason i ask is most control modules wont allow torque converter lock up until a certain engine temp is reached. Many units also delay shift and may even prevent top gear engagement until engine temp is about 120f-130f. How many miles on the unit? When was it serviced last? Maybe start a new thread if its going to get long. I'm sure some other members have some valuable input.
 
Messages
717
Location
MKE
For one year.It has got 167000 miles on it. I did 3 drains and refills using Redline's D4 6-7000 miles/4-5 months ago.The funny thing is that either I do not remember this happening with the old fluid or it just did not happen with it. Is 35 mph the phase where top gear engages?
 
Last edited:
Messages
26,152
Location
MA, Mittelfranken.de
Yes 30-35 MPH is about right. It sounds like its probably normal ECM/TCM programming to me. Does it feel like the engine is breaking loose and revving or more like it is just delaying going into the next gear? Did you do the filter in this unit? 3 drain and fills are expensive, this is a very easy unit to do a line off exchange on.
 
Messages
717
Location
MKE
Originally Posted By: Trav
Yes 30-35 MPH is about right. It sounds like its probably normal ECM/TCM programming to me. Does it feel like the engine is breaking loose and revving or more like it is just delaying going into the next gear? Did you do the filter in this unit? 3 drain and fills are expensive, this is a very easy unit to do a line off exchange on.
It does not sound like engine sound.But it increases when I press the accelerator but I let my foot off because I do not like the sound. No shaking, no jerking.Probably if I continue accelerating, not minding the sound, it will shift.The first 3 minutes of driving this happens and as far as I remember only when it is cold very early in the morning (4-5am). I did not drop the pan and replace the screen. It is expensive but I did not want to mess with the hoses, just scared.
 
Messages
26,152
Location
MA, Mittelfranken.de
Quote:
The first 3 minutes of driving this happens and as far as I remember only when it is cold
It sound like normal operation, obviously from here no one say 100%, keep an ear on it.
 
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